Authorities mixed up the identities of the lookalike students in the aftermath of the horrific crash and chaotic scene.

The families of the young women are raising publicity about a book they co-authored, "Mistaken Identity: Two Families, One Survivor, Unwavering Hope."

A two-hour "Dateline" NBC special is to be aired at 7 p.m. tonight.

Whitney Cerak said she believes God kept her "blindfolded" to the bizarre mix-up, leaving only memories of her family at her bedside.

After the mistake was discovered, the Van Ryns worried the Ceraks would be upset they were at their daughter's bedside, not them. Lisa Van Ryn also recalled it was difficult early on to visit Whitney Cerak.

"When we went back, she still looked like Laura," she said.

Though the VanRyn family had noted slight differences, they said they were told their daughter's appearance and behavior would be different because of her injuries.

Until concerns mounted toward the end of the five weeks, they never considered identification could be an issue.

"You see your daughter there, you just focus on her and what does she need?" said Laura's mother.

It was, added Laura's sister, a "puzzle we didn't know we were supposed to put together."

Today, Whitney Cerak said she has no lasting physical injuries, though her sense of humor took a while returning.

"Now," she said, "I feel like I'm completely there."

Sharing her story, and her faith, brings glory to God, she added.

"It's so humbling. The maker of heaven and Earth chose me, in a way."

Despite the loss, the VanRyns said they manage to find joy in life, and keep Laura in their thoughts and prayers. They talk about her every day.